The Defense of Marriage Act may have been passed in the US back in 1996, but the content of that law is now being opposed by Microsoft and a number of other companies and cities. This news was revealed in a amicus brief that was filed earlier this month but was formally revealed earlier this week.

The amicus brief, filed in the US Ninth District Court of Appeals, goes after the third portion of the Defense of Marriage Act, which defines marriage as being between a man and a woman. In the brief, Microsoft and the other companies included in the document state that the Act " ... forces us to discriminate against a class of our lawfully-married employees, upon whose welfare and morale our own success in part depends."

Besides Microsoft, the companies that joined in the amicus brief include Google, eBay, Electronic Arts, and Zynga. It also include the cities of New York, Boston, Los Angeles, Seattle and San Fransisco.

While the Defense of Marriage Act has been in place for over 15 years, the Obama Administration has said that it opposes the third portion of the act, feeling that it is unconstitutional. The administration said it would not defend the third part of the act in court on those grounds.